LONDON, Sept 15 (Reuters) - Nurses, midwives and cleaners working in Britain’s publicly-funded National Health Service (NHS) called on ministers to boost their salaries by 3.9 percent, in the latest push against a government-imposed cap on pay rises.

Public-sector pay was frozen for all but the lowest earners in 2010 and increases were limited to 1 percent a year from 2013 whilst inflation currently stands at 2.9 percent, having risen since last year’s Brexit vote.

Prime Minister Theresa May has been under increasing pressure to end the cap since her party lost its parliamentary majority in a snap election in June. Earlier this week, the government said it would boost pay for police and prison officers.

On Friday, fourteen unions wrote to finance minister Philip Hammond asking for a 3.9 percent pay rise and a further 800 pounds ($1,075) to reflect lost spending power over the last seven years of pay restraint.

“Health workers have gone without a proper pay rise for far too long. Their wages continue to fall behind inflation as food and fuel bills, housing and transport costs rise,” said the head of health at trade union UNISON Sara Gorton.

“NHS staff and their families need a pay award that stops the rot and starts to restore some of the earning that have been missing out on,” she said. ($1 = 0.7449 pounds) (Reporting by Costas Pitas; editing by Guy Faulconbridge)